HOME HELP CONTACT US SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Buff, P. R Articles by Ganjam, V. K Search for Related Content PubMed Articles by Buff, P. R Articles by Ganjam, V. K

¹ Departments of Biomedical Sciences,
² Veterinary Medicine and Surgery,
³ Animal Sciences, University of Missouri-Columbia, Columbia, Missouri 56211, USA

(Requests for offprints should be addressed to P R Buff who is now at Department of Animal and Dairy Sciences, Mississippi State University, Box 9815, Mississippi State, Mississippi 39762, USA; Email: pbuff{at}ads.msstate.edu)

Endocrine characteristics of Quarter Horse-type mares were determined during a 68 h feed deprivation and again in the same mares following surgical thyroidectomy (THX). A crossover experimental design was implemented, in which mares received brome hay available ad libitum (FED) or were food deprived (RES) for 68 h. Blood samples were collected every 20 min for 48 h, beginning 20 h after the onset of food deprivation. Concentrations of triiodothyronine and thyroxine were undetectable post-THX. Plasma concentrations of thyrotropin were greater post-THX versus pre-THX (P<0.001). Plasma concentrations of leptin were greater in the THX FED group than in the THX RES group (P< 0.01). The existence of leptin pulse secretion was found only in post-THX compared with the same horses pre-THX (P = 0.02). We theorize that non-pulsatile secretion of leptin may have contributed to the survival of this species, as it evolved in the regions of seasonal availability of food. Lack of pulsatile secretion of leptin may contribute to the accumulation of energy stores by modulating leptin sensitivity.